HUST 1017 Exact Cover (Dancing links)

1017-exact cover

Time limit:15 seconds Memory limit:128 MB

Self-assessment 6,110 commits 3,226 times through

Title Description

there is a n*m matrix with only 0s and 1s, (1 <= n,m <= 1000). An exact cover are a selection of rows such that every column have a 1 in exactly one of the selected rows. Try to find out the selected rows.

Input

There is multiply test cases. First line:two integers N, M; The following N Lines:every line first comes a integer C (1 <= C <=), represents the number of 1s in this row, Then comes C integers:the Index of the columns whose value was 1 in this row.

Output

First

output the number of rows in the selection and then output the index of the selected rows. If There is multiply selections, you should just output any of them. If There is no selection, just output "no".

Sample input

6 73 1 4 72 1 43 4 5 73 3 5 64 2 3 6 72 2 7

Sample output

3 2 4 6

Tips

Source

Dupeng

I have a very low IQ, looked at three days to learn, template validation questions.

Incidentally, this is the first a to be formally transferred to C + +.

1#include <iostream>2#include <cstdio>3 using    namespacestd;4 5 Const    intHEAD =0;6 Const    intN =1005;7 intMap[n][n];8 intU[n * n],d[n * n],l[n * n],r[n * n],h[n * n],c[n * n],ans[n *N];9 Ten voidIniintcol); One BOOLDancingintk); A voidOutputvoid); - voidRemoveintc); - voidResumeintc); the intMainvoid) - { -     intN,m,num,col; -     intCount,front,first; +  -      while(Cin >> N >>m) +     { A INI (m); at  -Count = m +1; -          for(inti =1; I <= N;i + +) -         { -CIN >>num; -Front = first =count; in              while(Num--) -             { toCIN >>Col; +  -U[count] =U[col]; theD[count] =Col; *L[count] =Front; $R[count] =First ;Panax Notoginseng  -D[u[col]] =count; theU[col] =count; +R[front] =count; A  theH[count] =i; +C[count] =Col; -Front =count; $Count + +; $             } -L[first] = count-1; -         } the         if(!dancing (1)) -cout <<"NO"<<Endl;Wuyi     } the  -     return    0; Wu } -  About voidIniintCol) $ { -U[head] = D[head] = H[head] = C[head] =HEAD; -R[head] =1; -L[head] =Col; A  +     intFront =HEAD; the      for(inti =1; I <= Col;i + +) -     { $U[i] = D[i] =i; theL[i] =Front; theR[i] =HEAD; theR[front] =i; theFront =i; -  inC[i] =i; theH[i] =0; the     } About } the  the BOOLDancingintk) the { +     intc =R[head]; -     if(c = =HEAD) the     {Bayi output (); the         return    true; the     } -  - Remove (c[c]); the      for(inti = d[c];i! = C;i =D[i]) the     { theANS[K] =H[i]; the          for(intj = r[i];j! = I;j =R[j]) - Remove (c[j]); the         if(Dancing (k +1)) the             return    true; the          for(intj = l[i];j! = I;j =L[j])94 Resume (c[j]); the     } the Resume (c[c]); the 98     return    false; About } - 101 voidOutputvoid)102 {103     inti,j;104      for(i =1; Ans[i];i + +); thecout << I-1<<" ";106      for(j =1; J < I-1; j + +)107cout << Ans[j] <<" ";108cout << Ans[j] <<Endl;109 } the 111 voidRemoveintc) the {113R[L[C]] =R[c]; theL[R[C]] =L[c]; the  the      for(inti = d[c];i! = C;i =D[i])117          for(intj = r[i];j! = I;j =R[j])118         {119D[U[J]] =D[j]; -U[D[J]] =U[j];121         }122 }123 124 voidResumeintc) the {126R[L[C]] =C;127L[R[C]] =C; - 129      for(inti = u[c];i! = C;i =U[i]) the          for(intj = r[i];j! = I;j =R[j])131         { theD[U[J]] =J;133U[D[J]] =J;134         }135}

HUST 1017 Exact Cover (Dancing links)